The invention relates to a device and a method for separately transporting substrates and can be used especially in the production of DVDs (digital versatile disks).
Especially in the production of DVDs it is of particular importance that two substrates, which are bonded to form a DVD, are kept apart during transport and are not mixed up.
In known transporting systems for the DVD process (Cube of the company Balzers, cf. DE-C2-42 35 677) the substrates for the DVD are supplied through one single lock station. In this case there is a risk that the different substrates are mixed up.
U.S. Pat. No. 4,969,790 discloses a device and a method for coating substrates in a vacuum chamber, wherein a rotatable substrate holder bears a plurality of substrate receivers adapted to transport substrates on a circular path from one lock station to an associated coating station and back to the same respective lock station.
Moreover, the prospectus Speedline, DVD-Speedline plus, Leybold Systems GmbH, 2/97 discloses a transporting system in which different substrates are transported by a rotational movement to different processing stations.
DE-C1-196 06 764 discloses a device for gripping, holding and/or transporting substrates. A substrate is transported by means of gripping elements from an input station to a plurality of processing stations arranged in a line or circle. A plurality of gripping arms can be adjusted in a horizontal and/or vertical direction. Some gripping elements can be adjusted together in a horizontal and/or vertical direction, and at least one gripping arm can be adjusted independently of the other gripping arms in at least one of the movement directions.
It is an object of the present invention to provide a device and a method for separately transporting substrates, wherein mixing-up of the substrates is reliably prevented.
The object is achieved with the features of the claims.
In achieving this object, the invention starts out from the following basic ideas.
Two input stations are arranged on a circular arc at a given angular distance xcex1. Moreover, at least two processing stations, which are spaced from each other by the given angle xcex1, can be provided on the arc of the circle. Grippers are provided on the same arc of the circle at the given distance xcex1 and can be simultaneously rotated around an axis through the center of said circle through an angle xcex2. Two grippers simultaneously take one substrate each and transport the substrates to the processing stations, e.g. by rotating the gripping arrangement through 120xc2x0. Then the grippers can transport the different substrates to two output stations. The grippers can take up new substrates so that the transport step can be repeated. It is also possible to transport the substrates directly to the output stations thereby avoiding the processing stations, e.g. by changing the direction of rotation or, if the direction of rotation is maintained, by a rotation through 240xc2x0. Preferably, the grippers make a pendulum movement. Two grippers transport the substrates from the input stations to the processing stations and two grippers from the processing stations to the output stations in a reciprocating movement.
The advantages of the present invention reside in that a mixing-up of the substrates is avoided.